Stadler



March 17, 1959 A. STADLER ADJUSTABLE PROPORTIONAL MIXING BURNER 2 Sheets -Sheet 1 FIG.

Filed Feb. 8, 1957 MT M N u a hl lfl l n I FIG. 2

INVENTOR: ALBERT STAD LER March 17, 1959 A. ISTADLER 2,877,838

ADJUSTABLE PROPORTIONAL MIXING BURNER Filed Feb. 8, 1957 2 Sheets-Sheet 2 FIG?) 56 62 20 92 24 26 62 In I 56 INVENTOR: ALBERT STADLER United States Patent ADJUSTABLE PROPORTIONAL MIXING BURNER Engineering Co., Rockford, 11]., a corporation of Illinois Application February 8, 1957, Serial No. 639,005 16 Claims. (Cl. 158-118) The present invention relates to burner constructions and more particularly to a fuel mixing burner construction of the jet inspirator type, which is to say that it is provided with a mixing passage, a suction chamber communicating with the inlet end of the mixing passage and adapted to be supplied with one of the fluid constituents of the fuel mixture, and a jet-producing nozzle for-dis 2,877,838 Patented Mar. 17, 1959 from its opposed wall whereby the width of the jet opening andof the Venturi discharge opening may be increased or decreased in size as desired by varying the transverse dimension thereof.

.A similar and related object of the invention is to provide a burner construction including a Venturi duct ca- Albert Stadler, Rockford, Ill., assignor to Eclipse Fuel pable of adjustment as set forth above and which is generally rectangular in cross section at its discharge end in any position of adjustment thereof so that the flame produced thereby will be of rectangular configuration. Another related object is to provide an adjustable Venturi duct assembly and an adjustable jet-producing throat assembly which cooperate with each other in the burner construction with which they are associated in such a manner that either one may be regulated to accommodate a. the operating characteristics of the other so that for any size of burner discharge opening a corresponding size of jet opening may be attained to produce optimum flame characteristics as, for example, maximum flame length and intensity. 1

The provision of a burner construction which is extremely compact in its design; one which is comprised of a minimum number-of moving parts and which, therefore, is unlikely to get out of order; one which is rugged and durable and which, therefore, is possessed of a relatively long life; one which is capable of being readily the induced fluid and having novel means associated therewith whereby the fuel and air ratio of the mixture flowing through the passage is subject to adjustment by varying the cross sectional area of the nozzle discharge opening to increase or decrease the velocity of air issuing from the jet, and also having novel means whereby the cross sectional area of the discharge outlet of the .passage may be varied to increase or decrease the capacity of the burner assembly, the two adjustments being independent of each other so that varying flame effects may be attained to accommodate varying operating requirements.

It is among the principal objects of the invention to provide a burner construction of this sort wherein .the inspirator action of the burner assembly is effected by the provision of a Venturi arrangement including an inwardly tapered air jet-producing throat assembly and an outwardly flared Venturi duct assembly, the twoassemblies being disposed in effective alignment and register with each other whereby the principles set forth in Bernoullis Theorem as applied to gases is applicable in assembled and disassembled for purposes of inspection, repair or replacement of parts; one which has a wide range of adjustment with a minimum of adjusting movements; and one which otherwise is well adapted to perform the services'requi'red of it are further desirable features which have been borne in mind in the production and development of the present invention.

Numerous other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the following description ensues.

In the accompanying two sheets of drawings forming a part of this specification a preferred embodiment of the invention has been shown.

In these drawings:

Fig. 1 is a top plan view of a proportional fuel mixing burner construction constructed in accordance with the that the increase in velocity of the air stream in the throat causes a decrease in pressure thereof. This decrease in air pressure in the throat region is utilized to draw gas into the stream for mixture with the air and subsequent passage of the mixed gases through the Venturi 'duct to the burner nozzle where the gases are ignited. Novel means are provided for shifting a portion of the wall of the throat and similar means are provided for shifting a portion of the wall of the Venturi duct so that the effective size of the air jet and of the Venturi discharge outlet, i. e., the burner nozzle, respectively may be independently varied to produce the aforementioned varying flame characteristics.

It is another important object of the invention to provide a burner construction of the character briefly outlined above in which the tapered throat assembly and r principles of the'present invention;

Fig. 2 is a sectional view taken substantially along the line 2-2 of Fig. 1;

Fig. 3 is an end view of the structure shown in Fig. 2;

Fig. 4 is a fragmentary bottom plan view of an air jetforming plate employed in connection with the invention; and I Fig. 5 is a fragmentary exploded side elevational view of a control linkage mechanism-employed in connection with the invention.

.Referring now to the drawings in detail, "the proportionalimixing burner construction illustrated in the drawings constitutes the preferred embodiment and it is designed for insertion into a furnace wall for the purpose of conducting a combustible mixturesuch as gas and air into the interior of the furnace. The burner assembly is comprised, in the main, .of a number of individual castings operatively assembled upon each other to produce .the compact and generally rectangular box-like structure shown in Figs. 1 to 3, inclusive.

The burner assembly involves in its general organization an upper casting 10, a lower casting 12, and a pair of side plates 14 and 16 which may be of cast construction'and which are secured to the castings 10 and 12 at the opposite sides thereof and serve to maintain the two castings in superimposed spaced relationship. The four castings 10, 12, 14 and 16, when assembled on each other provide; a generally tubular boxlike structure which is rectangular in' vertical transverse cross section and having associated therewith internal fixed and movable baffle devices providing adjustable air jet and Venturi openings the nature and function of which will be made clear presently. An end casting 18 which may appropriately be termed an inlet casting inasmuch as it constitutes a means for introducing both gas and air to the jet and venturi devices associated with the box-like structure 10, 12, 14, 16, is secured to the left hand end of this structure as viewed in Fig. 2. The five castings 10, 12, 14, 16 and 18 briefly outlined above constitute the stationary main body of the burner structure of the present invention.

As best seen in Fig. 2, the upper casting is formed with a flat top or outside wall 20' having an upstanding flange 24 extending along its rear edge, i. e., the left hand edge thereof as viewed in Fig. 2, the flange 24 constituting an attachment flange bymeans of which the castings 10 and 18 may be secured together. The casting 10 has a front wall 26 a rear wall 28 which is coplanar with the flange 24, and a divided bottom wall structure including a forward wall section 30 and a rear wall section 32, the various walls and wall sections 20, 26, 28, 30 and 32, in combination with the side plates or castings 14 and 16, defining an upper suction chamber 33. At the juncture between the top wall 20 and the front and rear walls 26 and 28, respectively, and on both sides of these walls, as well as at the medial regions of the top wall 20, small webs or ears 34 are provided which constitute anchoring lugs designed for threaded reception of fastening screws 36 which pass through the side walls 14 or 16, as the case may be, and which serve to maintain the castings 10,, 14 and 16 in their assembled relationship. The rear bottom wall section 32 is inclined forwardly and downwardly and this section constitutes the fixed top wall of a forwardly tapered variable orifice air jet-producing assembly designatedv in its entirety at 38. The jet. assembly 38, in addition to the fixed top wall 32, is comprised of two side walls each of which is formed by a portion of one of the side plates 14 or 16' as the case may. be, and an adjustable bottom wall 40 in the form of a tiltable plate which is carried by the lower casting 12 and mounted for rocking movement thereon in a manner that will be described subsequently. The jet assembly briefly described above provides a forwardly and inwardly tapered jet or throat passage 42 leading to aVenturi jet opening 44 the effective cross sectional area of which may be varied by adjusting the inclination of the plate 40.

The forward bottom wall section 30 of the casting 10 is inclined, rearwardly and downwardly and this section constitutes the fixed top wall of a forwardly and, outwardly flaring variable size Venturi duct assembly designated in its entirety at 46. The Venturi duct assembly 46, in addition. to the fixed top wall 30, is comprised of. two side walls each of which is formed by a portion of one of the. side plates 14 or 16, andjan adjustable bottom wall 48 in. the form of a tiltable. plate .sitnilarto. the. plate 40 and similarlymounted for rocking movement .on -.the-

lower casting 12.. The. Venturi tubeassembly justde scribed provides; aforwardly and outwardly 'flaredlmixs ing chamber and exhaust passage 50 terminating ina forward burner nozzle 52. which projects forwardly of the composite burning'casing'body and which has a discharge opening 54 the cross sectional area of which may be varied by adjusting the inclination of the plate 48. At its' seat end, the Venturi tube assembly provides an adjustable Venturi entrance opening 55 in register with the jet opening'44.

Referring now to Figs. 1 to'3, inclusive, the lower'casting 12 is'formed with a depending attachment flange 56 at the rear end thereof while each side casting or plate 14 and 16 is formed with a laterally extending attachment flange 58. The four attachment flanges 24, 56 and 58 constitute a marginal flange arrangement whereby the castings 10 and 12 may be. secured to a generally rectangular marginal attachment flange 60 provided on the inlet casting 18 at the forward end. thereof, suitable attachment bolts 62 being employed for clamping the parts in position.

The inlet casting 18 is in the form of a cup-shaped annulus having an outer generally cylindrical wall 64, a frusto-conical inner wall 66 and a connecting radial rear wall 68. The aforementioned attachment flange 60 extends radially outwardly from the front edge of the outer wall 64. The frusto-conical inner wall 66 affords a forwardly and inwardly tapered inlet passage 70 which is in register and communication with the jet passage 42. An attachment flange 72 is secured by bolts or other means to the front wall 68 and is threaded as at 74 to receive the end of an air conduit (not shown) by means of which air under pressure may be supplied to the burner assembly for mixing purposes.

The annular space 76 existing within the confines of the four walls 28, 68, 64 and 66 constitutes a gas inlet chamber having a gas inlet 78 which extends through the wall 64 of the casting 18 at one side thereof, the inlet opening being threaded as at 80'for connection to a suitable gas line (not shown) leading from a source of gas at atmospheric pressure, as, for example, from a suitable pressure regulating valve of the zero governor type.

The lower casting 12 in external appearances is somewhat similar to the upper casting 10 and has a bottom wall 82 and upstanding front and rear walls 84 and 86, respectively. The walls 82, 84 and 86, together with the side plates or castings 14 and 16, and the two adjustable walls or plates 40 and 48 define a lower suction chamber 88. The suction chamber 88 is in communication with the inlet chamber 76 in the casting 18 by means of a series of spaced passages 90 (Figs. 2 and 3). The upper suction chamber 33 similarly communicates with the inlet chamber 76 by meansof a series of spaced passages 92.

The two movable walls 40 and 48 may be regarded as constituting a composite top wall for the lower casting 12 in the same manner that the two fixed walls 32 and 30 are considered as constituting a composite bottom wall for the upper casting 10.

Referring now to Figs. 1 and 2, the lower casting 12 has its bottom wall 82 formed with a pair of thickened saddle or cradle portions and 102, the saddle 100 being formed adjacent the rear end of the casting and the saddle 102 being formed medially thereof. The saddle 100 serves to tiltably support the adjustable j'et bottom wall plate 40. The saddle 102 serves to similarly support the adjustable Venturi duct bottom wall plate 48. Accordingly, the saddle or cradle 100 is formed with an upwardly facing transversely extending seating trough or socket 103 designed for sealing sliding engagement with the underneath side of a semi-circular depending transverse rib 104 formed on the underneath side of the plate 40. The end regions of the rib 104 are cut away .or slotted. as ,at 106' and a pair of pivot pins 108. project across'the relieved areas, and receive thereover the eyelet portions 110 of a pair of eye bolts 112 and 113 respectively, the shank portions 114 and 115 respectively of which extend vertically through drilled. bores 116 and 116, respectively, formed in the saddle portion 100. A clamping nut 118. is threadedly received on the. lower end of each bolt 112 and 113 and, when tightened, serves to draw therib 104 downwardly into the cradle trough 102 so that the latter makes sealing and rocking engagement therewith, thereby enabling the plate 40 to be swung or tilted throughout a limited range of movement so that the same may be adjusted on the saddle 100 to attain a desired width at the jet opening 44. Adjustment of the angular. position of the plate 40 is attained by means of a centrally disposed linkage mechanism including a pair of links 120 and 121 respectively the upper ends of which are connected to a transverse stub shaft 122 supported between a pair of depending ears 124 and the lower ends of which are pivotally connected to a pair efsvas'ss of trunnions 126 carried on a block 128. The block 128 is formed with an opening 130 (Fig. 1) into which there extends the upper reduced end 132 of an adjusting screw 134. The screw 134 extends through and is threadedly received in an opening 136 formed in the bottom wall 82 of the casting 12 and a locking nut 138 serves, when tightened against the wall 82 to secure the adjusting screw 134 in any selected position of adjustment. From the above description, it will be seen that the elevation of the forward edge of the jet-forming plate 40 may be varied by rotating the adjusting screw 134 in one direction or the other to vary the size of the jet opening 44, the dotted and full line positions of the plate 40 in Fig. 2 representing two illustrative adjusted positions of the plate.

The plate 48 which forms the bottom wall of the mixing chamber and exhaust passage 50 is adjustably mounted on the saddle portion 102 of the casting 12 by mounting and adjusting means similar inits design and construction to the mounting and adjusting means respectively associated with the plate 40 and which, therefore, need not be described in detail. It is deemed sufficient, to avoid needless repetition of description, to apply similar reference numerals to the corresponding parts of the twosaddle and linkage assemblies. It will be seen, therefore, that since the links 121 are pivoted to the plate 48 at a region well forwardly of the saddle supported rib 104, turning movement of the adjusting screw 134 in one direction ,or the other will raise or lower the plate 48 and thereby decrease or increase, respectively the vertical width of the burner discharge opening 54. As shown in Figs. 1 and 3, the two side plates are formed with vertically disposed attachment flanges 139 by'means of which the entire burner assembly may be operatively applied to the fire wall of a furnace or other appliance with which'the assembly is associated. Adjacent the discharge end of the flared exhaust passage 50, the opposed fixed and movable walls 30 and 48, respectively, are provided with a relatively narrow forwardly and inwardly inclined ribs or lips 140 and 142, respectively, each rib being drilled to provide a series of spaced passages 144. The ribs 140 and 142 present obstructions to the free flow of mixed gas and air passing through the passage 50 along the upper and lower walls thereof and thus create small eddy currents at the regions on the fire wall side of the passage. These eddy currents are localized in the regions of the ribs and, inasmuch as they have slow internal velocity, flame pockets are created at these regions which will remain ignited regardless of the velocity of the gas and air mixture passing through the Venturi passage.

It is to be noted that the forward edge of the bottom wall section 32 of the upper casting projects inwardly of the burner assembly a greater distance than does the rear edge of the bottom wall section 30, or in other words, it projects slightly below the level of the bottom wall section 30. Similarly, the forward edge of the adjustable plate 40 projects slightly above the level of the rear edge of the adjustable plate 48 in any positions of adjustment of the two plates. By such an arrangement, the overall transverse area of the jet opening 44 is at all'times maintained smaller than the overall transverse area of the Venturi entrance opening 55 and, since the two openings are in register with each other, a true Venturi action will take place so that the low pressure gas existing within the suction chambers 33 and 88 will be drawn into the outwardly flared mixing and discharge passage 46. It is also to be noted that'the plate 48 is cradled on the saddle 102 at a region sufficiently close to the rear end thereof that the small diflerence in elevation of the rear edge of the plate 48 occasioned by adjustment of the plate through a limited small angle of rocking or tilting movement may be regarded as being negligible insofar as any increase or decrease in the size of the Ymturientrance opening 55 is concerned. The size of 6 the flame-producing burner discharge opening '54, how ever, may be appreciably varied.

In the operation of the burner assembly described above, the path of air is directly through the central portion of the assembly from the inlet passage 70 to the burner discharge opening 54. Air enters the tapered inlet passage 70 and, since the velocity of the air becomes greater as the jet decreases in cross sectional area, the air stream issues from the jet opening 44 with'high velocity. In accordance with Bernoullis Theorem, the pressure in the upper and lower suction chambers 33 and 88, respectively, is lowered and thus the gas contained in these chambers is drawn through the slot-like opening existing between the walls 30 and 32 in the case of the upper suction chamber 33 and the slot-like opening existing between the plates 40 and 48 in the case of the lower suction chamber 88, and is thereafter intimately mixed with the air issuing from the jet orifice44 prior to being conducted through the outwardly flared passage 50 to the burner nozzle 52. A constant supply of gas is maintained in the two suction chambers 33 and 88 by passage through the openings 92 and 90, respectively, from the gas inlet chamber 76.

It will be understood that adjustment of the size ofthe air jet-producing opening 44 and of the burner discharge opening 54 in the, manner described above will be carried out according to engineering exigencies within the knowledge of the operator of the burner. Various combinations of adjustments are possible and, in general, it'may be stated that the wider the burner discharge opening; the greater the capacity of the burner. This increase or decrease in burner capacity may be carried out without varying the air-gas mixture. Increasing the capacity of the burner by widening the burner discharge opening will, of course, lower the discharge pressure of the air-gas mixture. This pressure may, however, be restored simply by increasing the effective area of the air jet opening 44. Regardless of the particular capacity at which the burner assembly is operated, experience will dictate the adjustments which are to be made to attain a strong flame of rectangular cross section and desirable length.

In compliance with Title 35, U. S. Code, Sections 112, 113, a preferred embodiment of the invention has been shown in the accompanying drawings and described herein. It will be understood, however, that other ernbodiments are contemplated and that the invention is not to be limited to the exact arrangement of parts disclosed since various changes in the details of construction may be resorted to without departing from the spirit of the invention. Only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited. I I

Having thus described the invention what I claim as new and desire to secure by Letters Patent is:

1. A fuel mixing burner construction comprising a burner casing having top an bottom walls, parallel side walls, front wall means and rear wall means, a fixed composite partition wall structure extending between the front and rear wall means and defining thereabove an upper suction chamber, said fixed composite partition wall structure including a. forwardly and upwardly inclined forward-wall section and a forwardly and downwardly inclined rear wall section, the rear edge of said forward wall section being spaced from the forward edge of said rear wall section so as to define a narrow transverse slot therebetween, a composite adjustable partition wall structure extending between the front and rear walls below said fixed composite partition wall structure and defining therebelow a lower suction chamber, said adjustable partition wall structure including a movable rear wall section and a movable forward wall section, means pivotally supporting each of said movable wall sections for limited tilting movement about a transverse hori' zontal axis spaced from the forward edge thereof, said movable rear wall section'in any position of adjustment being inclined forwardly and upwardly, said movable forward wall section in any position of adjustment being inclined forwardly and downwardly, the rear edge of said movable forward wall section being spaced a slight distance from the forward edge of said movable rear wall section so as. to define a narrow transverse slot therebetween in any positions of adjustment of which the sections are capable, said fixed and movable rear wall sections, in combination with opposed portions of the side walls, defining a longitudinally extending forwardly and inwardly tapered air jet-producing duct, said fixed and movable forward wall sections, in combination with other opposed portions of the side walls, defining a forwardly and outwardly flared Venturi duct, said jet-producing and Venturi ducts being in substantial alignment and register, the forward end of said Venturi duct consituting a flameproducing burner nozzle, the rear end of said jet-producing duct constituting an inlet for air under pressure, there being inlet openings for a gaseous fuel in certain of said casing walls in communication with said upper and lower suction chambers respectively, and means for independently adjusting the positions of said movable wall sections.

2. A fuel mixing burner construction as set forth in claim 1 wherein the tilt axis for said forward movable wall section is disposed along the rear edge of the section whereby tilting movement of the section will vary the vertical dimension of said forward end of the Venturi duct.

3. A fuel mixing burner construction as set forth in claim 1 wherein the tilt axis for each movable wall section is disposed along the rear edge thereof whereby tilting movement of the rear movable section will vary the vertical dimension of the forward end of said jet-producing duct and whereby tilting movement of the forward movable section will vary the vertical dimension of said forward end of the Venturi duct while maintaining the vertical dimension of the rear end of said jet-producing duct substantially constant.

4. A fuel mixing burner construction as set forth in claim 1 wherein the walls which define both the jet-producing duct and the Venturi duct present plane inner surfaces whereby the cross sectional configuration of said ducts at any selected longitudinal region therealong is rectangular.

5. A fuel mixing burner construction comprising a burner casing of generally rectangular transverse cross section and having top and bottom walls, parallel side walls, front wall means and rear wall means, said walls andwall means defining therebetween an internal chamber, a fixed composite partition wall structure extending between the front and rear wall means within the chamber and defining with said front and rear wall means and top wall an upper suction chamber, said composite partition wall structure including a forwardly and upwardly inclined forward wall section and a forwardly and down,- wardly inclined rear wall section, the rear edge of, said forward wall section being spaced a slight distance from the forward edge of said rear wall section so as to define a narrow transverse slot therebetween, a composite adjustable partition wall structure extending between the front and rear wall means within the chamber below said fixed. partition wall structure and defining with said front and rear wall means and said bottom wall a lower suction chamber, said composite adjustable partition wall structure including a movable rear wall section and a movable forward wall section, means pivotally supporting each of said movable wall sections on said bottom wall for limited swinging movement about a horizontal transverse axis spaced from the forward edge thereof, said movable rear wall section in any position of adjustment thereof being inclined forwardly and upwardly and said movable forward wall section in any position of adjustment thereof being inclined forwardly and down; wardl gvthe rear edge of said, movable forward well see:

tion being spaced a slight distance from the forward edge of said movable rear wall section so as to define a narrow transverse slot therebetween in any positions of adjustment of which the sections are capable, said fixed and movable rear wall sections, in combination with opposed portions of the side walls, defining a longitudinally extending forwardly and inwardly tapered air jet-producing duct, said fixed and movable forward wall sections, in combination with other opposed portions of the side walls, defining a forwardly and outwardly flared Venturi duct, said jet-producing and Venturi ducts being in substantial alignment and register, the forward end of said Venturi duct constituting a flame-producing burner nozzle, the rear end of said jet-producing duct constituting an inlet for air under pressure, and an annular gas and air inlet casing secured to the front wall of the burner casing and defining therewith an annular gas inlet chamber these being openings in the burner casing front wall establishing communication between said latter chamber and each of said suction chambers, said inlet casing being formed with a central air inlet passage therethrough in communication with the rear end of said forwardly and inwardly tapered air jet-producing duct.

6. A fuel mixing burner construction as set forth in claim 5 wherein the central air inlet passage formed in said inlet casing is provided with forwardly and inwardly tapered walls which are, in effect, continuations of the walls of said tapered jet-producing duct.

7. A fuel mixing burner construction as set forth in claim 5 wherein the tilt axis for said forwardly movable wall section is disposed along the rear edge of the section whereby tilting movement of the section will vary the vertical dimension of said forward end of the Venturi duct to thus vary the flame characteristics at the burner nozzle.

8. A fuel mixing burner construction as set forth in claim 5 wherein the tilt axis for each movable wall section is disposed along the rear edge thereof whereby tilting movement of the rear movable section will vary the vertical dimension of the forward end of said jet-producing duct and whereby tilting movement of the forward movable section will vary the vertical dimension of said forward end of the Venturi duct while maintaining the vertical dimension of the rear end of said jet-producing duct substantially constant.

9. A fuel mixing burner construction comprising a burner casing of generally rectangular transverse cross section and having top and bottom walls, parallel side walls, front wall means and rear wall means, said walls and wall means defining therebetween an internal chamber, a fixed composite partition wall structure extending between the front and rear wall means within the chamber and defining with said front and rear wall means and top wall an upper suction chamber, said composite partition wall structure including a forwardly and upwardly inclined forward wall section and a forwardly and downwardly inclined rear wall section, the rear edge of said forward wall section being spaced a slight distance from the forward edge of said rear wall section so as to define a narrow transverse slot therebetween, a composite adjustable partition wall structure extending between the front and rear wall means within the chamber below said fixed partition wall structure and definingwith said front and rear wall means and said bottom. walla lower suction chamber, said adjustable partition wall structure including a movable rear wall section and a movable forward wall section, means pivotally support? ing each of said composite movable wall sections on said bottom wall for limited swinging movement about a horizontal transverse axis spaced from the forward edge thereof, said movable rear wall section in any position of adjustment thereof being inclined forwardly and upwardly and said movable forward wall section in any position of adjustment thereof being inclined forwardly and downwardly, the rear edge of said movable forward wall: secase'ase's tion being spaced a slight distance from the forward edge of said movable rear wall section so as to define a narrow transverse slot therebetween in any positions of adjustment of which the sections are capable, said fixed and movable rear wall sections, in combination with opposed portions of the side walls, defining a longitudinally extending forwardly and inwardly tapered air jet-producing duct, said fixed and movable forward wall sections, in combination with other opposed portions of the side walls, defining a forwardly and outwardly flared Venturi duct, said jet-producing and Venturi ducts being in substantial alignment and register, the forward end of said Venturi duct constituting a flame-producing burner nozzle, the rear end of said jet-producing duct constituting an inlet for air under pressure, there being gas inlet openings in said burner casing front wall in communication with said upper and lower suction chambers respectively, and means for independently adjusting the positions of said movable wall sections, the forward edge of said rear fixed wall section projecting a slight distance below the rear edge of said forward wall section, and the forward edge of said rear movable wall section projecting a slight distance above the rear edge of the forward movable wall sectionin any of the positions of adjustment of which the two movable sections are capable.

10. A fuel mixing burner construction as set forth in claim 9 wherein the walls which define both the jetproducing duct and the Venturi duct present plane inner surfaces whereby the cross sectional configuration of said ducts at any selected longitudinal region therealong is rectangular.

11. A fuel mixing burner construction as set forth in claim 9 wherein the tilt axis for each movable wall section is disposed along the rear edge thereof whereby tilting movement of the rear movable section will vary the vertical dimension of said forward end of the jet-producing duct and whereby tilting movement of the forward movable section will vary the vertical dimension of said forward end of the Venturi duct while maintaining the vertical dimension of the rear end of said jet-producing duct substantially constant.

12. A fuel mixing burner construction comprising a burner casing of generally rectangular transverse cross section and having top and bottom walls, parallel side walls, front wall means and rear wall means, said walls and wall means defining therebetween an internal chamber, a fixed composite partition wall structure extending between the front and rear wall means within the chamber and defining with said front and rear wall means and top wall a suction chamber, said composite partition wall structure including a forwardly and upwardly inclined forward wall section and a forwardly and downwardly inclined rear wall section, the rear edge of said forward wall section being spaced a slight distance from the forward edge of said rear wall section so as to define a narrow transverse slot therebetween, said bottom wall including a movable rear wall section and a movable forward wall section, means pivotally supporting each of said movable wall sections on said bottom wall for limited swinging movement about a horizontal transverse axis spaced from the forward edge thereof, said movable rear wall section in any position of adjustment thereof being inclined forwardly and upwardly and said movable forward wall section in any position of adjustment thereof being inclined forwardly and downwardly, the rear edge of said movable forward wall section being spaced a slight distance from the forward edge of said movable rear wall section so as to define a narrow transverse slot therebetween in any positions of adjustment of which the sections are capable, said fixed and movable rear wall sections, in combination with opposed portions of the side walls, defining a longitudinally extending forwardly and inwardly tapered air jet-producing duct, said fixed and movable forward wall sections, in combination with other opposed portions of the side walls, defining a forwardly and outwardly flared Venturi duct, said jet-producing and Venturi ducts being in substantial alignment and register, the forward end of said Venturi duct constituting a flame-producing burner nozzle, 'the rear end of said jet-producing duct constituting an inlet for air underpressnre, there being an inlet'opening for gaseous fuel in one of said casing walls in communication with said suction chamber, and means for adjusting the positions of said movable wall sections.

13. A fuel mixing burner construction as set forth in claim 12 wherein the walls which define both the jetproducing duct and the Venturi duct present plane inner surfaces whereby the cross-sectional configuration of said ducts at any selected longitudinal region therealong is rectangular.

14. A fuel mixing burner construction comprising a composite burner casing including an upper open-sided casting having a top wall and depending front and rear walls, a lower open-sided casting having a bottom wall and upstanding front and rear walls, said castings being disposed in abutting relationship with the free edges of the front and rear walls respectively being in contiguity, thereby defining a rectangular enclosure open at its sides, a pair of side plates closing the open side of said castings and of said enclosure to define an inner casing chamber, a fixed composite partition wall structure extending across said enclosure between the lower ends of said front and rear walls of the upper casting and including a forwardly and downwardly inclined rear wall section and a forwardly and upwardly inclined forward wall section, the rear edges of said forward wall section being spaced a slight distance from the forward edge of said rear wall section so as to define a narrow transverse slot therebetween, said fixed composite partition wall structure defining with said front and rear walls of the upper casting and with said side plates an upper suction chamber, a composite adjustable partition wall extending across said enclosure between the upper edges of the front and rear walls of the upper casting and defining with said front, rear and bottorn walls and side plates a lower suction chamber, said composite partition wall including a movable rear wall section and a movable forward wall section, means pivotably supporting each of said movable wall sections on said bottom wall for limited swinging movement about a horizontal transverse axis spaced from the forward edge thereof, said movable rear wall section in any position of adjustment thereof being inclined forwardly and upwardly and said forward movable wall section in any position of adjustment thereof being inclined forwardly and downwardly, the rear edge of said movable forward wall section being spaced a slight distance from the forward edge of said movable rearwall section. so as to define a narrow transverse slot therebetween in any positions of adjustment of the sections, said fixed and movable rear wall sections, in combination with said side plates, defining a forwardly and inwardly tapered air jet-producing duct, said fixed and movable forward wall sections, in combination with said side plates, defining a forwardly and outwardly flared Venturi duct in register and alignment with said jet-producing duct, the forward end of said Venturi passage constituting a flame-producing burner nozzle, the rear end of said jet-producing duct constituting an inlet for air under pressure, there being an inlet opening for gaseous fuel in the rear walls of said upper and lower castings respectively in communication with said upper and lower suction chambers respectively, and means for adjusting the positions of said movable wall sections.

15. A fuel .mixing burner construction as set forth in claim 14 wherein said adjusting means are independent of each other whereby the position of either movable wall section may be varied at will.

16. A fuel mixing burner construction as set forth in claim 14 wherein the walls which define both the jetproducing duct and the Venturi duct present plane inner surfaces whereby the cross-sectional configuration of said n ducts at any selected longitudinal region therealon gv. is 1,844,187 rectangular. 2,751,974 2,757,723 References Cited m the file 0f th1s patent UNITED STATES PATENTS 5 1,149,622 Bradshaw Aug. 10, 1915 17,993

1,298,805 Siebert Apr. 1, 1919 12 Smith Feb. 9, 1932, Stadler June 26, 1956 Schlitt Aug. 7, 1956 FOREIGN PATENTS Great Britain of 1915 

